Metamorphic Core Complex Dichotomy in the North American Cordillera Explained by Buoyant Upwelling in Variably Thick Crust
Metamorphic Core Complex Dichotomy in the North American Cordillera Explained by Buoyant Upwelling in Variably Thick Crust
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DOI：
10.1130/gsatg548a.1
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
A. Zuza;W. Cao
中科院分区：
文献类型：
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作者：
A. Zuza;W. Cao
北美科迪勒拉山脉的变质核杂岩（MCC）呈现出强烈的二分性。北部的变质核杂岩形成于古近纪法拉隆板块俯冲期间的增厚造山高原，间距较宽（约200千米），且向西南方向变新。相反，南部的变质核杂岩形成于较薄的地壳中，间距较窄（约50千米），在渐新世 - 中新世向区域伸展转换期间发育，且向西北方向变新。岩浆作用和冷却年龄的综合研究、模拟以及板块重建表明，变质核杂岩可能最初是由法拉隆板块后撤后软流圈上涌导致的下地壳加热所驱动的浮力穹隆。这些穹隆后来在中新世伸展作用下被剥露出来。古近纪分布较广的内陆穹隆上涌和相关的糜棱岩在时间上与中新世的拆离作用是解耦的，表现出两阶段的发育过程。渐新世 - 中新世紧密排列的前陆变质核杂岩显示出穹隆作用和拆离断层作用几乎是同步的。……的间距二分性
Metamorphic core complexes (MCC) in the North American Cordillera exhibit a strong dichotomy. Those in the north formed in a thickened orogenic plateau during Paleogene Farallon subduction, are widely spaced (~200 km), and young SW. Conversely, those in the south formed in thinner crust, are closely spaced (~50 km), developed during the Oligocene-Miocene transition to regional transtension, and young NW. Synthesis of magmatism and cooling ages, modeling, and plate reconstructions demonstrate that MCCs could have initiated as buoyant domes driven by lower-crust heating caused by asthenospheric upwelling after Farallon slab rollback. These domes were later exhumed by Miocene extension. The widely spaced Paleogene hinterland domal upwellings and associated mylonites were temporally decoupled from Miocene detachments, manifesting a two-stage development. The closely spaced Oligocene-Miocene foreland MCCs show almost synchronized doming and detachment faulting. The spacing dichotomy of